Multiple herbicide-resistant Junglerice (Echinochloa colona): Identification of genes potentially involved in resistance through differential gene expression analysis

Authors: Wright, Alice; RODRIGUEZ, MARIANELA - Basf Corporation North America; SASIDHARAN, RAJKUMAR - Basf Corporation North America; KOSKI, LIISA - Basf Corporation North America; PETERSON, DANIEL - Mississippi State University; Nandula, Vijay; Ray, Jeffery - Jeff; BOND, JASON - Mississippi State University; SHAW, DAVID - Mississippi State University

Submitted to: Weed Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/2/2018
Publication Date: 6/27/2018
Citation: Wright, A.A., Rodriguez-Carres, M., Sasidharan, R., Koski, L., Peterson, D.G., Nandula, V.K., Ray, J.D., Bond, J.A., Shaw, D.R. 2018. Multiple herbicide-resistant Junglerice (Echinochloa colona): Identification of genes potentially involved in resistance through differential gene expression analysis. Weed Science. 66:347-354.

Interpretive Summary: Herbicide resistance, and in particular multiple herbicide resistance, poses an ever increasing threat to food security. A junglerice plant with resistance to four herbicides, each representing different mechanisms of action, was identified in Sunflower County, MS. Scientists from the Crop Production Systems Research Unit (USDA-ARS), Stoneville, MS, BASF, Mississippi State University, and other USDA-ARS research units conducted dose responses on resistant and sensitive plants to the herbicides to determine the levels of resistance. Differential gene expression analysis of untreated resistant and sensitive plants revealed that two messenger RNA transcripts representing different genes were significantly increased in resistant plants compared to the sensitive plants. A transcript representing a third gene was decreased in the resistant plants relative to the sensitive plants. SNP analysis of cytochrome P450s identified 27 transcripts with SNPs of interest, two of which had a premature stop codon in the sensitive plants that was absent or reduced in frequency in the resistant plants. These genes will require further study to determine their exact role in the resistance mechanisms present in resistant plants.

Technical Abstract: Herbicide resistance, and in particular multiple herbicide resistance, poses an ever increasing threat to food security. A biotype of junglerice with resistance to four herbicides, imazamox, fenoxaprop-P-ethyl, quinclorac, and propanil, each representing different mechanisms of action, was identified in Sunflower County, MS. Dose responses were performed on the resistant biotype and a biotype sensitive to all four herbicides to determine the level of resistance. Application of a cytochrome P450 inhibitor, malathion, with the herbicides imazamox and quinclorac resulted in decreased resistance. Differential gene expression analysis of untreated resistant and sensitive plants revealed that two transcripts, a kinase and a glutathione-S-transferase were significantly upregulated in resistant plants compared to the sensitive plants. A third transcript, encoding an F-box protein, was downregulated in the resistant plants relative to the sensitive plants. Analysis of SNPs in cytochrome P450s in the resistant and sensitive biotypes revealed several nonsynonymous point mutations of interest. These candidate genes will require further study to elucidate the resistance mechanisms present in the resistant biotype.